The goal is to test the general hypothesis that a major component of the pathogenesis of wasting in infants with HIV infection is a multifaceted defect in amino acid metabolism the end result of which is a decrease in protein accretion, and an increased net loss of protein. Studies of whole body protein kinetics have been completed in 6 HIV-infected infants and 4 non-infected infants born to HIV-infected mothers. The results demonstrate that compared to non-infected controls, HIV-infected infants have a higher rate of protein breakdown and a negative or zero net protein synthesis. It has also been demonstrated that there is a lower intake of energy and protein in the HIV-infected infants. Plans call for continuation of measurements of whole body protein kinetics to reach a total of 8 HIV positive infants and 8 controls and to study and additional new group in which dietary energy and protein intakes of the infected group will be supplemented to equal the intakes of the non- infected, healthy controls.